Unit 6 How long have you been collecting shells?I. Teaching aims and teaching demands:In this unit students learn to talk about how long you have been doing things.II. Teaching key and difficult points: Vocabulary collect, inline, marathon, skate, stamp, shell, globe, monster,particularly, run out of, be interested in last year, times, numbers, How long…? student, school, birthday, penguin, hobby, kiteB. Target languageHow long have you been skating?I’ve been skating since nin..